1. Field of the Invention
The present invention relates to a seat slide apparatus, and more particularly to a seat slide apparatus comprising a lower rail mounted in a longitudinal direction of a floor surface for mounting a seat and an upper rail guided and supported on the lower rail so as to freely slide in a longitudinal direction and mounted to a side of a seat main body.
2. Description of the Related Art
In general, a seat for a vehicle is provided with a seat main body constituted by a seat cushion, a seat back stood at the back thereof so as to be freely rotated and adjusted, and the like, and supports the seat cushion or the like constituting the seat main body on the vehicle body floor surface via a longitudinal slide mechanism, thereby being structured such as to be adjusted so as to freely slide in a longitudinal direction of the vehicle body and being formed so as to variously modify a layout of the seat within a passenger""s room.
Further, as a longitudinal slide mechanism for the seat mentioned above, there is employed a seat slide apparatus which is formed to be long in the longitudinal direction on the vehicle body floor surface, is mounted on the vehicle body floor surface and is constituted by a lower rail provided substantially in the same height as that of a surface of a floor carpet and an upper rail mounted to the seat main body. Further, as described in Japanese Unexamined Patent Publication No. 9-95163, there is disclosed a structure in which a lock member is provided in the upper rail and the lower rail so as to adjust a sliding operation.
As shown in FIG. 1, in a conventional seat slide apparatus 1, a pair of left and right lower rails 2 are provided with main body portions 2a made by a metal plate member and formed in a substantially upward-C shape, and a pair of left and right engagement portions 3 inward bent from front end sides of both of side portions 2b of the main body portions 2a and downward directed, thereby forming opening portions at end portions of the engagement portions 3. Further, front end rear end portions of the lower rail 2 are adhered to the vehicle body floor surface via front and rear leg portions 4a and 4b. 
A pair of left and right upper rails 5 in the seat slide apparatus 1 are formed in a substantially inverse-T shape so as to be assembled in an inner portion of the lower rails 2, and engaged portions 7 are formed by both side portions 5b upward bent from front end sides of horizontal portions 5a in the upper rails 5. The engaged portions 7 are assembled so as to be capable of engaging with the engagement portions 3 in the side of the lower rails 2. Further, anchor members, shafts of a seat lifter, bases of a reclining mechanism and the like are mounted to substantially inverse-T shaped vertical portions 5a of the upper rails 5. A roller 9a is inserted between the lower rails 2 and the upper rails 5, and balls 9b are inserted between the engagement portions 3 and the engaged portions 7.
In the case that the lower rail 2 of the conventional seat slide apparatus 1 as mentioned above is formed long, it is complex to work the respective portions, and there is a problem of rattle in the respective portions due to a size error or the like. Further, there is a disadvantage that a weight is increased if it is intended to keep strength with respect to a load. Further, in the case that a peeling load is applied upward to the side of the upper rail 5 due to an impact load or the like, an upper portion of the lower rail 2 is opened, and there is a risk that the peeling strength is reduced. Further, in the case that the lower rail 2 is mounted to the side of the vehicle body floor surface, refuses on the floor surface drop down into the inner portion of the lower rail 2 from the opening portion of the lower rail 2, and there is a risk that a smooth sliding operation of the upper rail 5 can not be obtained. Further, it is impossible to suitably support a weight of a sitting person or the like and to obtain a simple and inexpensive structure.
The present invention is made by taking the problems mentioned above into consideration, and an object of the present invention is to provide a seat slide apparatus which can prevent an upper portion of a lower rail from opening so as to improve a peeling strength in the case that a peeling load is applied upward to a side of an upper rail due to an impact load or the like, can improve a strength of the lower rail so as to prevent the upper rail from deforming, can form an opening portion of the lower rail narrow so as to prevent refuses on a floor surface from dropping down into an inner portion of the lower rail from the opening portion of the lower rail, has a simple structure, requires no increase of a number of new parts and no additional operation, is inexpensive, can easily and rapidly execute a mounting operation, can obtain a smooth and stable sliding motion, and can reduce a sliding resistance so as to improve an operability.
According to a first aspect of the present invention, there is provided a seat slide apparatus comprising:
a lower rail mounted in a longitudinal direction of a seat mounting floor surface; and
an upper rail guided and supported so as to freely slide in a longitudinal direction on the lower rail and mounted to a side of a seat main body,
wherein the lower rail is provided with a main body portion formed in a substantially upward-C shape and a pair of right and left upper side portions extended inward from front end sides of both side portions in the main body portion so as to form an opening portion, slider receiving portions are formed in front end of both side portions in the main body portion, a first hook portion is formed in a front end portion in a side of the opening portion of the upper side portion, and second hook portions are formed in both side portions of the main body portion, and
wherein the upper rail has a main body portion formed in a substantially downward-C shape capable of being assembled in the lower rail, and a vertical wall protruding upward from a center of an upper wall in the main body portion and protruding upward from the opening portion of the upper side portion in the lower rail, slider receiving portions are formed in upper ends of both side portions in the main body portion of the upper rail, a first engagement portion engaged with the first hook portion of the lower rail is formed in the upper wall of the main body portion, a projection portion is formed in the first engagement portion so as to protrude to the side of the first hook portion, and second engagement portions engaged with the second hook portions in the lower rail are formed in the side of the front ends of both side portions in the main body portion of the upper rail.